1. Field of the Disclosure
The invention relates to a surface enhanced Raman spectroscopy (SERS) sensing substrate and the manufacturing method thereof for enhancing Raman signals of specimen to be sensed.
2. Brief Description of the Related Art
Raman in 1928 invented the Raman scattering method that utilizes scattering property of light for detecting the vibrational spectroscopy signals (Raman spectroscopy) of molecule. However, the relatively minuteness of cross section of molecule beam making the detection of Raman signals difficult causes replacement of this technology by near-infrared spectroscopy (NIRS).
After the lasers were invented in the 1960, the lasers have been used as excitation source in Raman spectroscopy since 1964 for magnifying the signals. But the Raman spectroscope is still more expensive than infra-red spectroscopy limiting its application. In 1974, M. Fleischmann et al. found out that the rough metal surface can enhance significantly Raman spectroscopy signals (M. Fleischmann, P. J. Hendra, and A. J. McQulillan, “Raman spectra of pyridine adsorbed at a silver electrode” Chem. Phys. Lett. 26, 123 (1974)) and developed the surface enhanced Raman spectroscopy (SERS). This research has brought a large amount of potential applications. The surface enhanced Raman spectroscopy has improved the differentiation capability of molecule vibrational identification in the chemistry and biological system. Recent research has indicated that introducing of single molecule Raman scattering further enhances the Raman signal sensitivity. This finding has therefore extended the areas of sensor application involving surface enhanced Raman spectroscopy.
The state-of-art Raman signal instrumentation includes (a) radiation source; (b) Raman sensor; and (c) detector, wherein the Raman sensor includes surface enhanced Raman spectroscopy sensing substrate. The substrate is exposed to the radiation source and generates the localized plasmonic field, and after the localized plasmonic field is coupled to the specimen molecule being analyze, Raman photons are produced and detected by the Raman photons. Raman spectroscopy, which concerns with inelastic scattering of photons of chemical component, has been a tool for analyzing chemical substances (e.g., biological molecule) other than a tool for analyzing the molecules adsorbed by a surface.
The wide application range of surface enhanced Raman spectroscopy includes at least fast medical detection, protein research, pharmaceuticals, scientific discernment, development of biotech medicine, medical detection, health monitoring, single molecule detection, water pollution detection, agricultural products inspection, organic substance detection, environment detection, verification of carbon nano-tube. In the current measuring methods, SERS is also expected to replace the Gas chromatography and High performance liquid chromatography (HPLC).
Large area, simple vapor deposition process has attained engraving technique, such as silver zig-zag structures (Yi-Jun Jen, Ching-Wei Yu, Yu-Hsiung Wang, and Jheng-Jie Jhou, “Shape effect on the real parts of equivalent permeability of chevron thin films of silver”, J. Nanophoton. 5, (2011)) and silver aligned nanorod arrays (Yi-Jun Jen, A. Lakhtakia, Ching-Wei Yu, and Chin-Te Lin, “Vapor-deposited thin films with negative real refractive index in the visible regime,” Opt. Express 17, 7784 (2009)).
Since the metallic nanopillar structure's localized electric field strength can effectively enhance the Raman signals, it is proved that the silver aligned nanorod arrays (U.S. Pat. No. 7,658,991 B2) and double layers (silver nanorod/zig-zag dielectric structure) (U.S. Pat. No. 7,956,995 B2) can be applied to SERS.
While preferred embodiments are depicted in the drawings, those embodiments are illustrative and are not exhaustive, and many other equivalent embodiments may be envisioned and practiced based on the present disclosure by persons skilled in the arts.